Tonight’s the night: SOI! (Saturn Orbit Insertion) Cassini has just passed through Saturn’s ring plane, and if it survived the crossing, should now be on the start of its SOI burn, a 96-minute engine firing which should slow the craft down enough for it to enter orbit around Saturn. SpaceflightNow has a Cassini SOI timetable in EDT, and a Cassini mission status center with live updates. The Planetary Society has a much more detailed timeline in UTC/PDT.
SOI burn time is the moment of truth for Cassini; this makes or breaks the mission, because if it fails to burn, the craft will be travelling too fast to enter orbit, and will fly past Saturn to be lost in deep space. (It’s not quite as easy as “Standard orbit, Mr. Sulu.”) There’s a time delay of about 80 minutes between here and Saturn, so when it starts sending back telemetry and science data again, we won’t know till the signals get here. Stupid light barrier.
(The image used above is a screenshot from my copy of Celestia, showing Cassini’s position, live, and the view of the planet and its rings. Unfortunately, Celestia for OS X is a bit out of date, so I’m not sure the downloaded Cassini orbit data is correct, and that’s definitely not what the spacecraft looks like. Still, close enough for the view.)